MongoDb管道聚合排序子子文档 [英] MongoDb Pipeline Aggregation sorting sub sub documents
问题描述
在尝试使用MongooseJs在Mongodb中按嵌套数组排序时，我遇到了一个小问题.
I've having a slight issue when trying to sort by a nested array in Mongodb using MongooseJs.
a)产品包含任务，每个任务都有子任务.
b)任务有订单&每个子任务(task.order和task.subtask.order)也是如此.
a) A product contains tasks, each task has subTasks.
b) The task has a order & so does each subTask (task.order & task.subtask.order).
以下是示例产品文档:
db.products.find({_id: ObjectId("554a13d4b692088a38f01f3b")})
结果:
{
"_id" : ObjectId("554a13d4b692088a38f01f3b"),
"title" : "product title",
"order" : 3,
"description" : "Description here ",
"status" : "live",
"tasks" : [
{
"title" : "task 1",
"description" : "task 1 desc",
"order" : 10,
"_id" : ObjectId("554a13d4b692088a38f01f3a"),
"status" : "live",
"subTasks" : [
{
"title" : "task 1 sub 1",
"content" : "aaa",
"order" : -2,
"_id" : ObjectId("554a13d4b692088a38f01f5a"),
"status" : "live"
},
{
"title" : "task 1 sub 2",
"content" : "aaa",
"order" : 1,
"_id" : ObjectId("554a13d4b692088a38f01f3a"),
"status" : "live"
},
{
"title" : "task 1 sub 4",
"content" : "aaa",
"order" : 8,
"_id" : ObjectId("554a13d4b692088a38f01f4a"),
"status" : "live"
},
{
"title" : "task 1 sub 3 ",
"content" : "aaa",
"order" : 2,
"_id" : ObjectId("5550d0a61662211332d9a973"),
"status" : "live"
}
]
},
{
"title" : "task 2",
"description" : "task desc 2",
"order" : 1,
"_id" : ObjectId("5550855f9ee2db4e3958d299"),
"status" : "live",
"subTasks" : [
{
"title" : "task 2 sub 1",
"content" : "bbb",
"order" : 1,
"_id" : ObjectId("55508f459ee2db4e3958d29a"),
"status" : "live"
}
]
},
{
"title" : "task 3",
"description" : "task 3 desc",
"order" : 2,
"_id" : ObjectId("5551b844bb343a620f85f323"),
"status" : "live",
"subTasks" : [
{
"title" : "task 3 sub 2",
"content" : "cccc",
"order" : 0,
"_id" : ObjectId("5551b88abb343a620f85f324"),
"status" : "live"
},
{
"title" : "task 3 sub 4",
"content" : "cccc",
"order" : 1,
"_id" : ObjectId("5551b8f1bb343a620f85f325"),
"status" : "hidden"
},
{
"title" : "task 3 sub 3",
"content" : "ccc",
"order" : 2,
"_id" : ObjectId("5551ba40bb343a620f85f327"),
"status" : "hidden"
},
{
"title" : "task 3 sub 1",
"content" : "cccc",
"order" : -1,
"_id" : ObjectId("5551bcb8c31283c051d30b7c"),
"status" : "hidden"
}
]
}
]
}
我正在使用Mongodb Aggregation管道订购任务&其中的子任务.这是我到目前为止的内容:
I'm using the Mongodb Aggregation pipeline to order the tasks & the subTasks within them. Here is what I have so far:
db.products.aggregate([
{
$project: {
"tasks" : 1
}
},
{
$match: {
_id: ObjectId("554a13d4b692088a38f01f3b")
}
},
{
$unwind: "$tasks"
},
{
$project: {
"tasks": 1,
"subTasks": 1
}
},
{
$unwind: "$tasks.subTasks"
},
{
$sort: {
"tasks.subTasks.order": 1
}
},
{
$sort: {
"tasks.order": 1
}
}
])
结果:
{
"result": [
{
"_id": ObjectId("554a13d4b692088a38f01f3b"),
"tasks": {
"title": "task 2",
"description": "task desc 2",
"order": 1,
"_id": ObjectId("5550855f9ee2db4e3958d299"),
"status": "live",
"subTasks": {
"title": "task 2 sub 1",
"content": "bbb",
"order": 1,
"_id": ObjectId("55508f459ee2db4e3958d29a"),
"status": "live"
}
}
},
{
"_id": ObjectId("554a13d4b692088a38f01f3b"),
"tasks": {
"title": "task 3",
"description": "task 3 desc",
"order": 2,
"_id": ObjectId("5551b844bb343a620f85f323"),
"status": "live",
"subTasks": {
"title": "task 3 sub 1",
"content": "cccc",
"order": -1,
"_id": ObjectId("5551bcb8c31283c051d30b7c"),
"status": "hidden"
}
}
},
{
"_id": ObjectId("554a13d4b692088a38f01f3b"),
"tasks": {
"title": "task 3",
"description": "task 3 desc",
"order": 2,
"_id": ObjectId("5551b844bb343a620f85f323"),
"status": "live",
"subTasks": {
"title": "task 3 sub 2",
"content": "cccc",
"order": 0,
"_id": ObjectId("5551b88abb343a620f85f324"),
"status": "live"
}
}
},
{
"_id": ObjectId("554a13d4b692088a38f01f3b"),
"tasks": {
"title": "task 3",
"description": "task 3 desc",
"order": 2,
"_id": ObjectId("5551b844bb343a620f85f323"),
"status": "live",
"subTasks": {
"title": "task 3 sub 4",
"content": "cccc",
"order": 1,
"_id": ObjectId("5551b8f1bb343a620f85f325"),
"status": "hidden"
}
}
},
{
"_id": ObjectId("554a13d4b692088a38f01f3b"),
"tasks": {
"title": "task 3",
"description": "task 3 desc",
"order": 2,
"_id": ObjectId("5551b844bb343a620f85f323"),
"status": "live",
"subTasks": {
"title": "task 3 sub 3",
"content": "ccc",
"order": 2,
"_id": ObjectId("5551ba40bb343a620f85f327"),
"status": "hidden"
}
}
},
{
"_id": ObjectId("554a13d4b692088a38f01f3b"),
"tasks": {
"title": "task 1",
"description": "task 1 desc",
"order": 10,
"_id": ObjectId("554a13d4b692088a38f01f3a"),
"status": "live",
"subTasks": {
"title": "task 1 sub 1",
"content": "aaa",
"order": -2,
"_id": ObjectId("554a13d4b692088a38f01f5a"),
"status": "live"
}
}
},
{
"_id": ObjectId("554a13d4b692088a38f01f3b"),
"tasks": {
"title": "task 1",
"description": "task 1 desc",
"order": 10,
"_id": ObjectId("554a13d4b692088a38f01f3a"),
"status": "live",
"subTasks": {
"title": "task 1 sub 2",
"content": "aaa",
"order": 1,
"_id": ObjectId("554a13d4b692088a38f01f3a"),
"status": "live"
}
}
},
{
"_id": ObjectId("554a13d4b692088a38f01f3b"),
"tasks": {
"title": "task 1",
"description": "task 1 desc",
"order": 10,
"_id": ObjectId("554a13d4b692088a38f01f3a"),
"status": "live",
"subTasks": {
"title": "task 1 sub 3 ",
"content": "aaa",
"order": 2,
"_id": ObjectId("5550d0a61662211332d9a973"),
"status": "live"
}
}
},
{
"_id": ObjectId("554a13d4b692088a38f01f3b"),
"tasks": {
"title": "task 1",
"description": "task 1 desc",
"order": 10,
"_id": ObjectId("554a13d4b692088a38f01f3a"),
"status": "live",
"subTasks": {
"title": "task 1 sub 4",
"content": "aaa",
"order": 8,
"_id": ObjectId("554a13d4b692088a38f01f4a"),
"status": "live"
}
}
}
],
"ok": 1
}
预期结果:
{
"_id": ObjectId("554a13d4b692088a38f01f3b"),
"title": "product title",
"order": 3,
"description": "Description here ",
"status": "live",
"tasks": [
{
"title": "task 2",
"description": "task desc 2",
"order": 1,
"_id": ObjectId("5550855f9ee2db4e3958d299"),
"status": "live",
"subTasks": [
{
"title": "task 2 sub 1",
"content": "bbb",
"order": 1,
"_id": ObjectId("55508f459ee2db4e3958d29a"),
"status": "live"
}
]
},
{
"title": "task 3",
"description": "task 3 desc",
"order": 2,
"_id": ObjectId("5551b844bb343a620f85f323"),
"status": "live",
"subTasks": [
{
"title": "task 3 sub 1",
"content": "cccc",
"order": -1,
"_id": ObjectId("5551bcb8c31283c051d30b7c"),
"status": "hidden"
},
{
"title": "task 3 sub 2",
"content": "cccc",
"order": 0,
"_id": ObjectId("5551b88abb343a620f85f324"),
"status": "live"
},
{
"title": "task 3 sub 3",
"content": "ccc",
"order": 2,
"_id": ObjectId("5551ba40bb343a620f85f327"),
"status": "hidden"
}{
"title": "task 3 sub 4",
"content": "cccc",
"order": 1,
"_id": ObjectId("5551b8f1bb343a620f85f325"),
"status": "hidden"
}
]
}{
"title": "task 1",
"description": "task 1 desc",
"order": 10,
"_id": ObjectId("554a13d4b692088a38f01f3a"),
"status": "live",
"subTasks": [
{
"title": "task 1 sub 1",
"content": "aaa",
"order": -2,
"_id": ObjectId("554a13d4b692088a38f01f5a"),
"status": "live"
},
{
"title": "task 1 sub 2",
"content": "aaa",
"order": 1,
"_id": ObjectId("554a13d4b692088a38f01f3a"),
"status": "live"
},
{
"title": "task 1 sub 3 ",
"content": "aaa",
"order": 2,
"_id": ObjectId("5550d0a61662211332d9a973"),
"status": "live"
},
{
"title": "task 1 sub 4",
"content": "aaa",
"order": 8,
"_id": ObjectId("554a13d4b692088a38f01f4a"),
"status": "live"
}
]
}
]
我真的很接近，所有订购似乎都可以正常进行.我只需要一些帮助，即可将subTask放回父级中.任何帮助都将不胜感激.
I'm really close, all the ordering seems to be working. I just need some help to put the subTasks back inside the parents. Any help greatly appreciated.
谢谢
推荐答案
您从聚合管道的开始就犯了一个错误
You are making a mistake right from the beginning of your aggregation pipeline
$project: {
"tasks" : 1
}
，您将丢失所有数据.因此，首先您需要保留它:
by which you lose all your data. So first of all you need to reserve it doing:
$project: {
tasks: 1,
doc: {
title: "$title",
order: "$order",
description: "$description",
status: "$status"
}
}
然后像在问题中一样执行您的$unwind:
Afterwards perform your $unwinds as you do in your question:
{$unwind: "$tasks"}, {$unwind: "$tasks.subTasks"}
然后进行排序.您需要使用复合键进行排序，否则，按tasks.order排序后，按tasks.subTasks.order进行的排序将不成立.所以:
Then do the sorting. You need to do the sorting with compound keys, otherwise the ordering by tasks.subTasks.order will not hold as soon as you sort by tasks.order. So:
{$sort: {"tasks.order": -1, "tasks.subTasks.order": 1}}
然后是困难的部分.您需要$group备份结果，第一步是$push备份subTasks，但是首先，再次需要保留任务属性:
And then comes the hard part. You need to $group back the results, and the first step is to $push back the subTasks, but first of all, again you need to preserve the task attributes:
$project: {
doc: 1,
task_id: "$tasks._id",
tasks_doc: {
title: "$tasks.title",
description: "$tasks.description",
order: "$tasks.order",
status: "$tasks.status"
},
subTasks: "$tasks.subTasks"
}
...收集subTasks:
$group: {
_id: {
_id: "$_id",
task_id: "$task_id",
doc: "$doc",
task_doc: "$tasks_doc"
},
subTasks: {
$push: "$subTasks"
}
}
与tasks相同.请注意，在$group期间，您还需要向后投射task_doc属性:
And the same for the tasks. Pay attention that during the $grouping you also need to project back the task_doc attributes:
$group: {
_id: {
_id: "$_id._id",
doc: "$_id.doc"
},
tasks: {
$push: {
_id: "$_id.task_id",
title: "$_id.task_doc.title",
description: "$_id.task_doc.description",
order: "$_id.task_doc.order",
status: "$_id.task_doc.status"
subTasks: "$subTasks"
}
}
}
然后投影出根doc属性:
$project: {
_id: "$_id._id",
title: "$_id.doc.title",
description: "$_id.doc.description",
order: "$_id.doc.order",
status: "$_id.doc.status",
tasks: 1
}
基本上就是这样.这是完整的原始聚合管道，因此您可以测试并查看是否获得期望的结果:
That is basically it. Here is the full raw aggregation pipeline, so you can test and see whether you get the desired result:
[
{$match: {_id: ObjectId("554a13d4b692088a38f01f3b")}},
{$project: {tasks: 1, doc: {title: "$title", order: "$order", description: "$description", status: "$status"}}},
{$unwind: "$tasks"},
{$unwind: "$tasks.subTasks"},
{$sort: {"tasks.order": -1, "tasks.subTasks.order": 1}},
{$project: {doc: 1, task_id: "$tasks._id", tasks_doc: {title: "$tasks.title", description: "$tasks.description", order: "$tasks.order", status: "$tasks.status"}, subTasks: "$tasks.subTasks"}},
{$group: {_id: {_id: "$_id", task_id: "$task_id", doc: "$doc", task_doc: "$tasks_doc"}, subTasks: {$push: "$subTasks"}}},
{$group: {_id: {_id: "$_id._id", doc: "$_id.doc"}, tasks: {$push: {_id: "$_id.task_id", title: "$_id.task_doc.title", description: "$_id.task_doc.description", order: "$_id.task_doc.order", status: "$_id.task_doc.status", subTasks: "$subTasks"}}}},
{$project: {_id: "$_id._id", title: "$_id.doc.title", description: "$_id.doc.description", order: "$_id.doc.order", status: "$_id.doc.status", tasks: 1}}
]
更新
如果数组字段为空或不存在(为null)，则对该字段的$unwind操作.请注意，必须在每个数组$unwind之前执行此$project ion.
If an array field is empty or does not exist (is null) the $unwind operation on that field will return empty result. The solution to this situation is initially setting up the null/empty field to some zero value, e.g. "<empty-array>". Note, that you have to do this $projection for each array, before its $unwind.
看看此答案有关如何使用$ifNull运算符的信息.另外，请在此处签出.
Take a look at this answer about how to use the $ifNull operator. Also check out the $size operator here.
处理完此部分后，您需要$group返回结果，这可以使用值
After dealing with this part, you need to $group back the results, and this can be achieved using the $cond operator, to check against the "<empty-array>" value
这篇关于MongoDb管道聚合排序子子文档的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
